crl.report 2. composite wood-iron objects

8/7/2019 CRL.report 2. Composite Wood-iron Objects

1/7

Conservation Research Laboratory Reports

Composite wood / iron objects: pole arms and partisans

La Salle Shipwreck Project

Texas Historical Commission

Throughout each year, the Conservation Research Laboratory conserves material from anumber of different archaeological projects. The purpose of these CRL reports is to showcase theconservation procedures used to treat some of the more interesting archaeological material. Theconservation of a partisan found on the Belle is presented in this report. The Belle, one of theships of French explorer Robert Cavelier, Sieur (Lord) de La Salle, was lost in Matagorda Bay,Texas in 1686. It was excavated by the Texas Historical Commission.

During any shipwreck conservation project, and the Belle is no exception, there are alwaysartifacts classified as composite artifacts because they are comprised of disparate materials thatcannot be disassembled or broken down into their component parts. A number of pole armsfound on the Belle fall into this category as they all have iron blades attached to long wooden

shafts.

Definition of Terms

A 'pole arm' is an all-inclusive word for any metal pointedshaft used for military and/or status purposes. There isconsiderable confusion and overlapping of definitions forthe numerous 15th- through 18th-century wooden shaftswith metal pointed ends. They are referred to as pikes,spontoons, partisans, and halberds to name but a few.

The encrusted object to the left was recovered from

theBelle

. It can be identified as a partisan, which isdefined either as "a weapon used by infantry in the 16thto 17th centuries, consisting of a long-handled spear, the

blade having one or more lateral cuttingprojections" (Oxford Universal Dictionary of Historical

Principles 1955) or as "a broad-bladed pole arm usuallyhaving short, curved branches at the base of the blade;

but the shapes of the blades vary greatly" (Stone1961:484).

A partisan, Stone (1961:484) continues, is"particularly the weapon of the guards of dignitaries andmany specimens are elaborately decorated. It was usedthroughout the 16th and 17th centuries and still is used

as a ceremonial weapon."

The encrusted pole arm/partisan shown above is an excellent example of an iron/woodcomposite artifact. It is presented here as an interesting example of the role that casting in

epoxy plays in modern conservation. Casting is of particular importance in the conservation ofthe Belle's iron artifacts, for only a natural mold formed by the encrustation is all that remains ofa significant percentage of them -- especially the smaller objects. It is important to rememberthat when a metal object is lost in the sea, a layer of encrustation begins to form immediately on

Pgina 1 de 3Conservation Research Laboratory - Center for Maritime Archaeology and Conservatio...

04/02/2011http://nautarch.tamu.edu/crl/Report2/polearm.htm


2/7

its surfaces. This encrustation creates a perfect impression (in many instances) and mold of theoriginal metal object.

In order to properly evaluate the encrusted pole arm, it was necessary to first obtain a goodset of radiographs. Where sound metal remains on an encrusted artifact, it shows as a whitearea on a radiograph, for X rays do not readily penetrate through metal and thus only slightlyexpose the X-ray film. Areas where metal is completely corroded are indicated by a grayshadow.

In the case of the Belle pole arm, we coulddetermine from the radiograph (illustrated atright) that some metallic iron remained in thethick, center part of the blade. However, nometal remained along the blade's thin cutting

edges. In short, all that remained of the bladewas a hollow mold filled with loose slush. We

decided then to make a cast of the blade from theimpression it had left in the encrustation.

The figure to the right was drawn from X rays ofthe encrusted object. It can be classed as a

partisan, since it is very similar to the examplehighlighted in the figure below.




3/7

Source: Stone 1961:483.

The highlighted partisan (left) is a 17th-centuryFrench piece. The other examples show the rangevariations found within this interesting partisan clas

of polearms.Elaborate etched designs are evident on some of

these examples.

See how we conserved the iron blade.

See how we conserved the wooden shaft.

This site is maintained by the staff of the Nautical Archaeology Program ([email protected]). The contents of this site - text, images, anddata - are intended for personal information only. Downloading of information or graphic images contained herein for private use is not discouraged;

however, written permission from the Nautical Archaeology Program is required for the publication of any material. Any use of this material should creditthe Nautical Archaeology Program, Texas A&M University. For additional details, contact Donny L. Hamilton ([email protected]). For prices forpublishing rights to photographs and video from the Conservation Research Laboratory and the Port Royal Project, click here. All La Salle shipwreck

images and data contained within this web site are copyrighted 1999 Texas Historical Commission. You are free to use information or non-copyrightedimages from these pages for any non-commercial purpose. Any use of this information should credit the Texas Historical Commission. Last updated:

Wednesday, 19-Jan-2011 17:50:05 Central Standard Time




4/7





CONSERVATION OF AN IRON BLADE

Radiographs (right) of encrusted metal artifacts, such as the partisan(below), can reveal where sound metal remains, as well as show

areas of metal that have since corroded. It is sometimes difficult,however, to determine from the X rays if the corrosion products are

solid or if they are merely loose slush. To find out, the conservatorhas no choice but to break open the encrustation. If all that remains

is loose slush and a natural mold of the artifact, the mold can beeasily cast in epoxy. If the corrosion products are solid, a different

tactic must be used.

When the encrusted partisan (above) was broken in half, we realized that the corrosion productswere, in fact, solid. Our original plan of casting the entire piece had to be slightly modified.

After the broken encrustation was fitted back together, it was pressed into a box containing plaster-of-

Paris (below left). The plaster supported the back half of the encrusted piece, while the conservator slowlyremoved the encrusted top half. The conservator used an S.S. White Airbrasie unit to cut through the

encrustation (below right). The precision of this tool ensured that the thin cutting edge of the partisanblade would not be inadvertently destroyed.


04/02/2011http://nautarch.tamu.edu/crl/Report2/polearm1.htm


5/7

.

After cutting off the top surface of the encrustation, all of the metal corrosion layers were removed.Special care was taken to clean the sharp edges of the blade. Hysol LE-6329 NA epoxy (no longer available)

was poured into the open areas, making sure it flowed along the edges. The different pieces of the topencrustation were then placed on top of the epoxy, so that it would pick up the natural surface of the

original blade surface.

Part epoxy/part metal partisanremoved from the encrustation

Silicone rubber mold made of part

metal/part epoxy partisan




6/7

Part metal/metal oxide and part expoxy partisan asremoved from the encrustation after filling voids with epoxy

Silicone rubber mold cast with Hysol LE 63epoxy

After the epoxy set, the

cast was removed and

covered with a coating of

graphite to give it ametallic appearance

(right). There isadditional work to be

done on the metal strapsthat project from the

partisan, connecting it tothe shaft.

See how we conserved the wooden shaft.

Find out more aboute pole arms and partisans.

This site is maintained by the staff of the Nautical Archaeology Program ([email protected]). The contents of this site - text, images, and data - are intendedfor personal information only. Downloading of information or graphic images contained herein for private use is not discouraged; however, written permission from theNautical Archaeology Program is required for the publication of any material. Any use of this material should credit the Nautical Archaeology Program, Texas A&M

University. For additional details, contact Donny L. Hamilton ([email protected]). For prices for publishing rights to photographs and video from the ConservationResearch Laboratory and the Port Royal Project, click here. All La Salle shipwreck images and data contained within this web site are copyrighted 1999 Texas HistoricalCommission. You are free to use information or non-copyrighted images from these pages for any non-commercial purpose. Any use of this information should credit theTexas Historical Commission. Last updated: Wednesday, 19-Jan-2011 17:50:05 Central Standard Time




7/7





CONSERVATION OF A WOOD SHAFT

Throughout the conservation process, the wood shaft part of the partisan had been kept wet bywrapping it in damp rags. It was conserved only after the blade was cast. The encrustationaround the wood was carefully removed using a mechanical air scribe. Silicone oil was used totreat the wood in this instance, although acetone-rosin would have been just as appropriate.Both are very good when the wood to be preserved is broken in several pieces and has to berepaired. PEG was not appropriate as conservation treatment in this case, since there was somemetallic iron remaining on the blade. PEG attacks and can be potentially damaging to ironunless specific precautions are taken.

Once the partisan was cast and the wooden handle conserved, final photographs and

drawings were made of the reconstructed complete piece. Observations, such as the successrate of the treatment used and the final appearance of the object, were also included in theconservation record. The notes made before, during, and after the conservation process aid inthe analysis of artifacts.

See how we conserved the iron blade.

Find out more aboute pole arms and partisans.

This site is maintained by the staff of the Nautical Archaeology Program ([email protected]). The contents of this site - text, images, and

data - are intended for personal information only. Downloading of information or graphic images contained herein for private use is not discouraged;

however, written permission from the Nautical Archaeology Program is required for the publication of any material. Any use of this material should creditthe Nautical Archaeology Program, Texas A&M University. For additional details, contact Donny L. Hamilton ([email protected]). For prices for

publishing rights to photographs and video from the Conservation Research Laboratory and the Port Royal Project, click here. All La Salle shipwreckimages and data contained within this web site are copyrighted 1999 Texas Historical Commission. You are free to use information or non-copyrighted

images from these pages for any non-commercial purpose. Any use of this information should credit the Texas Historical Commission. Last updated:Wednesday, 19-Jan-2011 17:50:05 Central Standard Time


crl.report 2. composite wood-iron objects

Documents